Our studies demonstrated specific insulin receptors on isolated glomeruli. We showed that the majority of the glomerular surface receptors on endothelial cells. The endothelium acts as an interface between the blood and the glomerular mesangium, therefore insulin binding to endothelial cell receptors may affect the mesangial cells. Insulin may mediate the production of nitric oxide, a potent vasoconstrictor for mesangial cells, through stimulation of amino acid uptake. To understand if the insulin receptor is dysfunctional in diabetes, we are currently isolating endothelial cells from non-obese diabetic mice for further studies on the insulin receptor.